Boris Johnson is back in the lead in the race for Mayor of London according to the latest YouGov poll for the Evening Standard.
In the first round Boris would be ahead of Ken Livingstone by 46% to 45%. In the run off Boris would win by 51% to 49%. This is a reverse of the poll position last month. But the margin is so narrow it is reasonable to say the race is "effectively" neck and neck.
Factors which may have shifted support to Boris in the last month include the cut in the Council Tax precept, diminishing trust in Livingstone's pledge to cut fares and offence at Livingstone's remark about the Conservatives being "riddled" with gays.